Thread: GIOChannel problem

I want to execute a program from my GTK+ application and get it's stdout output. After a little research I've turned to glibs GIOChannel. But I can't figure it out how can I detect the end of input. The only way I can think of is calling "wait_pid" with WNOHANG from my callback function, but somehow I think there's better way... Can anyone point me in the right direction?
That's what I have so far:

Code:

#include <glib.h>

#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>

GIOChannel *io_channel_open(char *cmd[]);
gboolean cb_read_line(GIOChannel *io_channel, GIOCondition condition, gpointer data);

int main(int argc, char *argv[])
{
    GMainLoop *main_loop;
    GIOChannel *io_channel;
    char *cmd[] = {"ls", "-lah", NULL};

    io_channel = io_channel_open(cmd);
    g_io_add_watch(io_channel, G_IO_IN, cb_read_line, NULL); /* Adds 1 reference...*/
    g_io_channel_unref(io_channel); /* ... so we don't need this one, I think */

    /* Main Loop */
    main_loop = g_main_loop_new(NULL, TRUE);
    g_main_loop_run(main_loop);

    return 0;
}

/* Executes the program described by cmd[]
 * and creates GIOChannel
 */
GIOChannel *io_channel_open(char *cmd[])
{
    GIOChannel *io_channel;
    pid_t child_pid;
    int   fd_pipe[2];

    pipe(fd_pipe);
    child_pid = fork();

    if (child_pid == 0) {
        close(fd_pipe[0]);
        dup2(fd_pipe[1], STDOUT_FILENO);

        execvp(cmd[0], cmd);
        g_error("exec() failed!\n");
        abort();
    }
    else {
        close(fd_pipe[1]);
        io_channel = g_io_channel_unix_new(fd_pipe[0]);

        return io_channel;
    }
}

/* Callback function to read and
 * process the input
 */
gboolean cb_read_line(GIOChannel *io_channel, GIOCondition condition, gpointer data)
{
    gchar *line_buf;
    gsize length, terminator_pos;

    g_io_channel_read_line(io_channel, &line_buf, &length, &terminator_pos, NULL);
    g_print("%s", line_buf);

    /* In _theory_ I should return FALSE to destroy this io_channel. */
    return TRUE;
}

I'm using to compile:

Code:

gcc -Wall -o pipe_koe main.c `pkg-config --cflags --libs glib-2.0`

hmm... it seems I haven't been reading glib reference manual close enouhg. I just needed to add watch for hangup condition (G_IO_HUP).